<!DOCTYPE html>
<html lang="en-US">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width,initial-scale=1">
    <title>面试官：说说你对正则表达式的理解？应用场景？ | 前端档案</title>
    <meta name="generator" content="VuePress 1.8.2">
    <link rel="icon" href="/favicon.ico">
    <meta name="description" content="前端通关宝典">
    <meta name="theme-color" content="#3eaf7c">
    <meta name="apple-mobile-web-app-capable" content="yes">
    <meta name="apple-mobile-web-app-status-bar-style" content="black">
    
    <link rel="preload" href="/assets/css/0.styles.e02fc531.css" as="style"><link rel="preload" href="/assets/js/app.bf44e39b.js" as="script"><link rel="preload" href="/assets/js/2.db7a59af.js" as="script"><link rel="preload" href="/assets/js/140.22839840.js" as="script"><link rel="prefetch" href="/assets/js/10.3bbe2f24.js"><link rel="prefetch" href="/assets/js/100.43061c81.js"><link rel="prefetch" href="/assets/js/101.2e8a188c.js"><link rel="prefetch" href="/assets/js/102.3f4f14f0.js"><link rel="prefetch" href="/assets/js/103.5ed45f48.js"><link rel="prefetch" href="/assets/js/104.29ef9283.js"><link rel="prefetch" href="/assets/js/105.e4051d70.js"><link rel="prefetch" href="/assets/js/106.ec073f00.js"><link rel="prefetch" href="/assets/js/107.9b165150.js"><link rel="prefetch" href="/assets/js/108.c0031864.js"><link rel="prefetch" href="/assets/js/109.06bb75a7.js"><link rel="prefetch" href="/assets/js/11.402e3434.js"><link rel="prefetch" href="/assets/js/110.edc92528.js"><link rel="prefetch" href="/assets/js/111.e50e0cca.js"><link rel="prefetch" href="/assets/js/112.b0decdf4.js"><link rel="prefetch" href="/assets/js/113.f0801886.js"><link rel="prefetch" href="/assets/js/114.25ab8fa4.js"><link rel="prefetch" href="/assets/js/115.36fc62f3.js"><link rel="prefetch" href="/assets/js/116.8df9a6aa.js"><link rel="prefetch" href="/assets/js/117.1ec0fada.js"><link rel="prefetch" href="/assets/js/118.51c54869.js"><link rel="prefetch" href="/assets/js/119.d708669d.js"><link rel="prefetch" href="/assets/js/12.eba9a66a.js"><link rel="prefetch" href="/assets/js/120.a44efeea.js"><link rel="prefetch" href="/assets/js/121.581a4ae4.js"><link rel="prefetch" href="/assets/js/122.e54e19e1.js"><link rel="prefetch" href="/assets/js/123.62aa41d0.js"><link rel="prefetch" href="/assets/js/124.c51c6b7f.js"><link rel="prefetch" href="/assets/js/125.68055811.js"><link rel="prefetch" href="/assets/js/126.8b16d246.js"><link rel="prefetch" href="/assets/js/127.fc7608d6.js"><link rel="prefetch" href="/assets/js/128.0df431fc.js"><link rel="prefetch" href="/assets/js/129.77241cfd.js"><link rel="prefetch" href="/assets/js/13.a3e65817.js"><link rel="prefetch" href="/assets/js/130.2bf0b622.js"><link rel="prefetch" href="/assets/js/131.77da1093.js"><link rel="prefetch" href="/assets/js/132.c1ac84bc.js"><link rel="prefetch" href="/assets/js/133.001af559.js"><link rel="prefetch" href="/assets/js/134.98ff69db.js"><link rel="prefetch" href="/assets/js/135.b91963f4.js"><link rel="prefetch" href="/assets/js/136.e3df531a.js"><link rel="prefetch" href="/assets/js/137.157c5a5f.js"><link rel="prefetch" href="/assets/js/138.1d3a1791.js"><link rel="prefetch" href="/assets/js/139.9e17df54.js"><link rel="prefetch" href="/assets/js/14.bd9cc5f8.js"><link rel="prefetch" href="/assets/js/141.dbde614d.js"><link rel="prefetch" href="/assets/js/142.5a6858ba.js"><link rel="prefetch" href="/assets/js/143.e26d707c.js"><link rel="prefetch" href="/assets/js/144.5b1fbe13.js"><link rel="prefetch" href="/assets/js/145.09921e20.js"><link rel="prefetch" href="/assets/js/146.8ea606b7.js"><link rel="prefetch" href="/assets/js/147.41bda9d5.js"><link rel="prefetch" href="/assets/js/148.d89f18bc.js"><link rel="prefetch" href="/assets/js/149.16aa39c9.js"><link rel="prefetch" href="/assets/js/15.deb2f25a.js"><link rel="prefetch" href="/assets/js/150.07798494.js"><link rel="prefetch" href="/assets/js/151.6732ee94.js"><link rel="prefetch" href="/assets/js/152.c644167e.js"><link rel="prefetch" href="/assets/js/153.040f256b.js"><link rel="prefetch" href="/assets/js/154.1cec3035.js"><link rel="prefetch" href="/assets/js/155.a4b51a17.js"><link rel="prefetch" href="/assets/js/156.095b78e0.js"><link rel="prefetch" href="/assets/js/157.eb262a26.js"><link rel="prefetch" href="/assets/js/158.35756e8c.js"><link rel="prefetch" href="/assets/js/159.6ac43664.js"><link rel="prefetch" href="/assets/js/16.c7b17381.js"><link rel="prefetch" href="/assets/js/160.0a56c40c.js"><link rel="prefetch" href="/assets/js/161.8320b48a.js"><link rel="prefetch" href="/assets/js/162.09ba1172.js"><link rel="prefetch" href="/assets/js/163.f7fb82e8.js"><link rel="prefetch" href="/assets/js/164.ab9df42b.js"><link rel="prefetch" href="/assets/js/165.f012858f.js"><link rel="prefetch" href="/assets/js/166.b3f190e3.js"><link rel="prefetch" href="/assets/js/167.43b66e59.js"><link rel="prefetch" href="/assets/js/168.4eb162d3.js"><link rel="prefetch" href="/assets/js/169.0375d2cf.js"><link rel="prefetch" href="/assets/js/17.da61c942.js"><link rel="prefetch" href="/assets/js/170.90c9c235.js"><link rel="prefetch" href="/assets/js/171.672fc257.js"><link rel="prefetch" href="/assets/js/172.dfa9d8d9.js"><link rel="prefetch" href="/assets/js/173.61a6ec8e.js"><link rel="prefetch" href="/assets/js/174.4f4ef0d7.js"><link rel="prefetch" href="/assets/js/175.675d01d1.js"><link rel="prefetch" href="/assets/js/176.5bd1bcb7.js"><link rel="prefetch" href="/assets/js/177.4355dadd.js"><link rel="prefetch" href="/assets/js/178.79ed29b8.js"><link rel="prefetch" href="/assets/js/179.2247dc30.js"><link rel="prefetch" href="/assets/js/18.6e554767.js"><link rel="prefetch" href="/assets/js/180.db79361a.js"><link rel="prefetch" href="/assets/js/181.85a33295.js"><link rel="prefetch" href="/assets/js/182.0bc317bc.js"><link rel="prefetch" href="/assets/js/183.7769a38e.js"><link rel="prefetch" href="/assets/js/184.9b0aba05.js"><link rel="prefetch" href="/assets/js/185.f6dc87bd.js"><link rel="prefetch" href="/assets/js/186.e3b7de00.js"><link rel="prefetch" href="/assets/js/187.a6dadcea.js"><link rel="prefetch" href="/assets/js/188.d3f8b0e3.js"><link rel="prefetch" href="/assets/js/189.1112499f.js"><link rel="prefetch" href="/assets/js/19.f800e0d1.js"><link rel="prefetch" href="/assets/js/190.e3255e84.js"><link rel="prefetch" href="/assets/js/191.34deece6.js"><link rel="prefetch" href="/assets/js/192.69821c0e.js"><link rel="prefetch" href="/assets/js/193.769a5088.js"><link rel="prefetch" href="/assets/js/194.afaa2cde.js"><link rel="prefetch" href="/assets/js/195.5b94bbc6.js"><link rel="prefetch" href="/assets/js/196.3b078264.js"><link rel="prefetch" href="/assets/js/197.2d9585d3.js"><link rel="prefetch" href="/assets/js/198.3095d8b8.js"><link rel="prefetch" href="/assets/js/199.79b6db11.js"><link rel="prefetch" href="/assets/js/20.4a74a968.js"><link rel="prefetch" href="/assets/js/200.c309ef7a.js"><link rel="prefetch" href="/assets/js/201.bded46e8.js"><link rel="prefetch" href="/assets/js/202.801fb3ea.js"><link rel="prefetch" href="/assets/js/203.b9933f5e.js"><link rel="prefetch" href="/assets/js/204.255b43df.js"><link rel="prefetch" href="/assets/js/205.000fb7ac.js"><link rel="prefetch" href="/assets/js/206.8f945829.js"><link rel="prefetch" href="/assets/js/207.74942b2e.js"><link rel="prefetch" href="/assets/js/208.329d8230.js"><link rel="prefetch" href="/assets/js/209.3fc54586.js"><link rel="prefetch" href="/assets/js/21.5f725cbd.js"><link rel="prefetch" href="/assets/js/210.1aa9659f.js"><link rel="prefetch" href="/assets/js/211.702df03f.js"><link rel="prefetch" href="/assets/js/212.ca95f208.js"><link rel="prefetch" href="/assets/js/213.024b4fa6.js"><link rel="prefetch" href="/assets/js/214.e2830dd8.js"><link rel="prefetch" href="/assets/js/215.0b646cb4.js"><link rel="prefetch" href="/assets/js/216.9bd6d019.js"><link rel="prefetch" href="/assets/js/217.586593b4.js"><link rel="prefetch" href="/assets/js/218.a2244829.js"><link rel="prefetch" href="/assets/js/219.1d858220.js"><link rel="prefetch" href="/assets/js/22.7d2b7a74.js"><link rel="prefetch" href="/assets/js/220.7f5e3dbd.js"><link rel="prefetch" href="/assets/js/221.d1f79d31.js"><link rel="prefetch" href="/assets/js/222.51d8a12c.js"><link rel="prefetch" href="/assets/js/223.797028ea.js"><link rel="prefetch" href="/assets/js/224.d925bf8b.js"><link rel="prefetch" href="/assets/js/225.cfe12606.js"><link rel="prefetch" href="/assets/js/226.b6bd41b4.js"><link rel="prefetch" href="/assets/js/227.15412d16.js"><link rel="prefetch" href="/assets/js/228.66af5157.js"><link rel="prefetch" href="/assets/js/229.cfb11559.js"><link rel="prefetch" href="/assets/js/23.1409c9f4.js"><link rel="prefetch" href="/assets/js/230.d2e613b5.js"><link rel="prefetch" href="/assets/js/231.85b8958b.js"><link rel="prefetch" href="/assets/js/232.42df48c8.js"><link rel="prefetch" href="/assets/js/233.d3be0c78.js"><link rel="prefetch" href="/assets/js/234.bb68d0be.js"><link rel="prefetch" href="/assets/js/235.bfd00052.js"><link rel="prefetch" href="/assets/js/236.3d58cc9d.js"><link rel="prefetch" href="/assets/js/237.d9af6062.js"><link rel="prefetch" href="/assets/js/238.54894974.js"><link rel="prefetch" href="/assets/js/239.b69669d0.js"><link rel="prefetch" href="/assets/js/24.e06b2b32.js"><link rel="prefetch" href="/assets/js/240.44f7b333.js"><link rel="prefetch" href="/assets/js/241.2d307b1a.js"><link rel="prefetch" href="/assets/js/242.47aecf42.js"><link rel="prefetch" href="/assets/js/243.b5afbb6e.js"><link rel="prefetch" href="/assets/js/244.8e04094f.js"><link rel="prefetch" href="/assets/js/245.78009475.js"><link rel="prefetch" href="/assets/js/246.eb7991c2.js"><link rel="prefetch" href="/assets/js/247.00c024fd.js"><link rel="prefetch" href="/assets/js/248.144c2842.js"><link rel="prefetch" href="/assets/js/249.35bae652.js"><link rel="prefetch" href="/assets/js/25.5e7aeaa8.js"><link rel="prefetch" href="/assets/js/250.854bde18.js"><link rel="prefetch" href="/assets/js/251.7cbb77f8.js"><link rel="prefetch" href="/assets/js/252.1ed96448.js"><link rel="prefetch" href="/assets/js/253.9d736b7d.js"><link rel="prefetch" href="/assets/js/254.137c6595.js"><link rel="prefetch" href="/assets/js/255.ac6865dc.js"><link rel="prefetch" href="/assets/js/256.055e06fd.js"><link rel="prefetch" href="/assets/js/257.63559614.js"><link rel="prefetch" href="/assets/js/258.b6958ba1.js"><link rel="prefetch" href="/assets/js/259.bc6da491.js"><link rel="prefetch" href="/assets/js/26.77d42111.js"><link rel="prefetch" href="/assets/js/260.a8e9559d.js"><link rel="prefetch" href="/assets/js/261.b051c6dd.js"><link rel="prefetch" href="/assets/js/262.e83c7ca8.js"><link rel="prefetch" href="/assets/js/263.bd14a165.js"><link rel="prefetch" href="/assets/js/264.65c3b624.js"><link rel="prefetch" href="/assets/js/265.db4371b9.js"><link rel="prefetch" href="/assets/js/266.97118d6c.js"><link rel="prefetch" href="/assets/js/267.de83cb0b.js"><link rel="prefetch" href="/assets/js/268.2bdd86cb.js"><link rel="prefetch" href="/assets/js/269.9c9a802f.js"><link rel="prefetch" href="/assets/js/27.fa37605f.js"><link rel="prefetch" href="/assets/js/270.f599f9fe.js"><link rel="prefetch" href="/assets/js/271.275d4619.js"><link rel="prefetch" href="/assets/js/272.ed0fabf6.js"><link rel="prefetch" href="/assets/js/273.fc279fbe.js"><link rel="prefetch" href="/assets/js/274.fe4b3d21.js"><link rel="prefetch" href="/assets/js/275.922677e1.js"><link rel="prefetch" href="/assets/js/276.597ceb81.js"><link rel="prefetch" href="/assets/js/277.71871d2e.js"><link rel="prefetch" href="/assets/js/278.10923657.js"><link rel="prefetch" href="/assets/js/279.cddbf2d7.js"><link rel="prefetch" href="/assets/js/28.7418a003.js"><link rel="prefetch" href="/assets/js/280.66542c64.js"><link rel="prefetch" href="/assets/js/281.c7ca5292.js"><link rel="prefetch" href="/assets/js/282.d105ef08.js"><link rel="prefetch" href="/assets/js/283.ae8d69c7.js"><link rel="prefetch" href="/assets/js/284.8763c337.js"><link rel="prefetch" href="/assets/js/285.cce4e007.js"><link rel="prefetch" href="/assets/js/29.42b5bf54.js"><link rel="prefetch" href="/assets/js/3.a2af090e.js"><link rel="prefetch" href="/assets/js/30.7fe0ece5.js"><link rel="prefetch" href="/assets/js/31.e05d012e.js"><link rel="prefetch" href="/assets/js/32.0a6466c6.js"><link rel="prefetch" href="/assets/js/33.8db270b1.js"><link rel="prefetch" href="/assets/js/34.c6e6ae70.js"><link rel="prefetch" href="/assets/js/35.8fc12d56.js"><link rel="prefetch" href="/assets/js/36.cb54baf3.js"><link rel="prefetch" href="/assets/js/37.656cb8eb.js"><link rel="prefetch" href="/assets/js/38.9152ff6b.js"><link rel="prefetch" href="/assets/js/39.f71e5e3d.js"><link rel="prefetch" href="/assets/js/4.02de3c47.js"><link rel="prefetch" href="/assets/js/40.3d664ab4.js"><link rel="prefetch" href="/assets/js/41.fc6e4f78.js"><link rel="prefetch" href="/assets/js/42.c17c3353.js"><link rel="prefetch" href="/assets/js/43.e78a329f.js"><link rel="prefetch" href="/assets/js/44.326a0948.js"><link rel="prefetch" href="/assets/js/45.67e6e1d4.js"><link rel="prefetch" href="/assets/js/46.85f71b1e.js"><link rel="prefetch" href="/assets/js/47.f2e524a6.js"><link rel="prefetch" href="/assets/js/48.843108ee.js"><link rel="prefetch" href="/assets/js/49.98713c95.js"><link rel="prefetch" href="/assets/js/5.f38c3daa.js"><link rel="prefetch" href="/assets/js/50.2c70898f.js"><link rel="prefetch" href="/assets/js/51.023fea5d.js"><link rel="prefetch" href="/assets/js/52.3877af4c.js"><link rel="prefetch" href="/assets/js/53.3938d117.js"><link rel="prefetch" href="/assets/js/54.4cf45721.js"><link rel="prefetch" href="/assets/js/55.6894de94.js"><link rel="prefetch" href="/assets/js/56.48fd0f63.js"><link rel="prefetch" href="/assets/js/57.2c3b8155.js"><link rel="prefetch" href="/assets/js/58.fee976b4.js"><link rel="prefetch" href="/assets/js/59.d57c3ac9.js"><link rel="prefetch" href="/assets/js/6.a7d50f34.js"><link rel="prefetch" href="/assets/js/60.9954df49.js"><link rel="prefetch" href="/assets/js/61.1b870f60.js"><link rel="prefetch" href="/assets/js/62.37537ac3.js"><link rel="prefetch" href="/assets/js/63.5e7cfac8.js"><link rel="prefetch" href="/assets/js/64.407003ca.js"><link rel="prefetch" href="/assets/js/65.ba6c5d7d.js"><link rel="prefetch" href="/assets/js/66.2b5a751b.js"><link rel="prefetch" href="/assets/js/67.2faf15d0.js"><link rel="prefetch" href="/assets/js/68.19e50dcb.js"><link rel="prefetch" href="/assets/js/69.eec003cb.js"><link rel="prefetch" href="/assets/js/7.6c196c91.js"><link rel="prefetch" href="/assets/js/70.98d2461a.js"><link rel="prefetch" href="/assets/js/71.184225a4.js"><link rel="prefetch" href="/assets/js/72.956d136a.js"><link rel="prefetch" href="/assets/js/73.3e68378e.js"><link rel="prefetch" href="/assets/js/74.cec669e7.js"><link rel="prefetch" href="/assets/js/75.d418b5f0.js"><link rel="prefetch" href="/assets/js/76.f3f9ccd6.js"><link rel="prefetch" href="/assets/js/77.f24df03b.js"><link rel="prefetch" href="/assets/js/78.7eee67a8.js"><link rel="prefetch" href="/assets/js/79.8fadb3f7.js"><link rel="prefetch" href="/assets/js/8.b7eb2fb2.js"><link rel="prefetch" href="/assets/js/80.4f6165b0.js"><link rel="prefetch" href="/assets/js/81.49b03807.js"><link rel="prefetch" href="/assets/js/82.7ea07224.js"><link rel="prefetch" href="/assets/js/83.d6bd71b7.js"><link rel="prefetch" href="/assets/js/84.26db1aa8.js"><link rel="prefetch" href="/assets/js/85.c8f1f3bb.js"><link rel="prefetch" href="/assets/js/86.fd1c3c7f.js"><link rel="prefetch" href="/assets/js/87.38ab6ed9.js"><link rel="prefetch" href="/assets/js/88.f0a874e0.js"><link rel="prefetch" href="/assets/js/89.2b3352d4.js"><link rel="prefetch" href="/assets/js/9.d7ae4925.js"><link rel="prefetch" href="/assets/js/90.286cc7d4.js"><link rel="prefetch" href="/assets/js/91.c17c366b.js"><link rel="prefetch" href="/assets/js/92.29bc2389.js"><link rel="prefetch" href="/assets/js/93.6d335097.js"><link rel="prefetch" href="/assets/js/94.89ab26c7.js"><link rel="prefetch" href="/assets/js/95.f2493183.js"><link rel="prefetch" href="/assets/js/96.6662ec36.js"><link rel="prefetch" href="/assets/js/97.22c9d3f9.js"><link rel="prefetch" href="/assets/js/98.0b0b77a2.js"><link rel="prefetch" href="/assets/js/99.df5f5981.js">
    <link rel="stylesheet" href="/assets/css/0.styles.e02fc531.css">
  </head>
  <body>
    <div id="app" data-server-rendered="true"><div class="theme-container"><header class="navbar"><div class="sidebar-button"><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" role="img" viewBox="0 0 448 512" class="icon"><path fill="currentColor" d="M436 124H12c-6.627 0-12-5.373-12-12V80c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12z"></path></svg></div> <a href="/" class="home-link router-link-active"><img src="/images/logo.png" alt="前端档案" class="logo"> <span class="site-name can-hide">前端档案</span></a> <div class="links"><div class="search-box"><input aria-label="Search" autocomplete="off" spellcheck="false" value=""> <!----></div> <nav class="nav-links can-hide"><div class="nav-item"><a href="/guide/" class="nav-link">
  指南
</a></div><div class="nav-item"><a href="/fe/" class="nav-link router-link-active">
  前端
</a></div><div class="nav-item"><a href="/be/" class="nav-link">
  后端
</a></div><div class="nav-item"><a href="/base/" class="nav-link">
  基础
</a></div><div class="nav-item"><a href="/tools/" class="nav-link">
  工具
</a></div><div class="nav-item"><a href="/resume/" class="nav-link">
  简历
</a></div><div class="nav-item"><a href="/experience/" class="nav-link">
  面经
</a></div><div class="nav-item"><a href="/technology/" class="nav-link">
  八股文
</a></div><div class="nav-item"><a href="/thinks/" class="nav-link">
  思考
</a></div> <!----></nav></div></header> <div class="sidebar-mask"></div> <aside class="sidebar"><nav class="nav-links"><div class="nav-item"><a href="/guide/" class="nav-link">
  指南
</a></div><div class="nav-item"><a href="/fe/" class="nav-link router-link-active">
  前端
</a></div><div class="nav-item"><a href="/be/" class="nav-link">
  后端
</a></div><div class="nav-item"><a href="/base/" class="nav-link">
  基础
</a></div><div class="nav-item"><a href="/tools/" class="nav-link">
  工具
</a></div><div class="nav-item"><a href="/resume/" class="nav-link">
  简历
</a></div><div class="nav-item"><a href="/experience/" class="nav-link">
  面经
</a></div><div class="nav-item"><a href="/technology/" class="nav-link">
  八股文
</a></div><div class="nav-item"><a href="/thinks/" class="nav-link">
  思考
</a></div> <!----></nav>  <ul class="sidebar-links"><li><a href="/fe/" aria-current="page" class="sidebar-link">大前端学习路径 + B站资源整合</a></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>HTML</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>CSS</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading open"><span>JavaScript</span> <span class="arrow down"></span></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/fe/javascript/" aria-current="page" class="sidebar-link">问题汇总</a></li><li><a href="/fe/javascript/array_api.html" class="sidebar-link">数组的常用方法</a></li><li><a href="/fe/javascript/string_api.html" class="sidebar-link">面试官：JavaScript字符串的常用方法有哪些？</a></li><li><a href="/fe/javascript/type_conversion.html" class="sidebar-link">面试官：谈谈 JavaScript 中的类型转换机制</a></li><li><a href="/fe/javascript/==_===.html" class="sidebar-link">面试官：== 和 ===区别，分别在什么情况使用</a></li><li><a href="/fe/javascript/clone.html" class="sidebar-link">深浅拷贝</a></li><li><a href="/fe/javascript/closure.html" class="sidebar-link">面试官：说说你对闭包的理解？闭包使用场景</a></li><li><a href="/fe/javascript/scope.html" class="sidebar-link">面试官：说说你对作用域链的理解</a></li><li><a href="/fe/javascript/prototype.html" class="sidebar-link">原型、原型链</a></li><li><a href="/fe/javascript/inherit.html" class="sidebar-link">面试官：Javascript如何实现继承？</a></li><li><a href="/fe/javascript/this.html" class="sidebar-link">this</a></li><li><a href="/fe/javascript/context_stack.html" class="sidebar-link">面试官：JavaScript中执行上下文和执行栈是什么？</a></li><li><a href="/fe/javascript/event_Model.html" class="sidebar-link">面试官：说说JavaScript中的事件模型</a></li><li><a href="/fe/javascript/typeof_instanceof.html" class="sidebar-link">面试官：typeof 与 instanceof 区别</a></li><li><a href="/fe/javascript/event_agent.html" class="sidebar-link">面试官：解释下什么是事件代理？应用场景？</a></li><li><a href="/fe/javascript/new.html" class="sidebar-link">面试官：说说new操作符具体干了什么？</a></li><li><a href="/fe/javascript/ajax.html" class="sidebar-link">面试官：ajax原理是什么？如何实现？</a></li><li><a href="/fe/javascript/bind_call_apply.html" class="sidebar-link">面试官：bind、call、apply 区别？如何实现一个bind?</a></li><li><a href="/fe/javascript/regexp.html" aria-current="page" class="active sidebar-link">面试官：说说你对正则表达式的理解？应用场景？</a><ul class="sidebar-sub-headers"><li class="sidebar-sub-header"><a href="/fe/javascript/regexp.html#一、是什么" class="sidebar-link">一、是什么</a></li><li class="sidebar-sub-header"><a href="/fe/javascript/regexp.html#二、匹配规则" class="sidebar-link">二、匹配规则</a></li><li class="sidebar-sub-header"><a href="/fe/javascript/regexp.html#三、匹配方法" class="sidebar-link">三、匹配方法</a></li><li class="sidebar-sub-header"><a href="/fe/javascript/regexp.html#str-replace-regexp" class="sidebar-link">str.replace(regexp)</a></li><li class="sidebar-sub-header"><a href="/fe/javascript/regexp.html#四、应用场景" class="sidebar-link">四、应用场景</a></li><li class="sidebar-sub-header"><a href="/fe/javascript/regexp.html#参考文献" class="sidebar-link">参考文献</a></li></ul></li><li><a href="/fe/javascript/event_loop.html" class="sidebar-link">事件循环机制</a></li><li><a href="/fe/javascript/Dom.html" class="sidebar-link">面试官：DOM常见的操作有哪些？</a></li><li><a href="/fe/javascript/BOM.html" class="sidebar-link">面试官：说说你对BOM的理解，常见的BOM对象你了解哪些？</a></li><li><a href="/fe/javascript/tail_recursion.html" class="sidebar-link">面试官：举例说明你对尾递归的理解，有哪些应用场景</a></li><li><a href="/fe/javascript/memory_leak.html" class="sidebar-link">面试官：说说 JavaScript 中内存泄漏的几种情况？</a></li><li><a href="/fe/javascript/cache.html" class="sidebar-link">面试官：Javascript本地存储的方式有哪些？区别及应用场景？</a></li><li><a href="/fe/javascript/functional_programming.html" class="sidebar-link">面试官：说说你对函数式编程的理解？优缺点？</a></li><li><a href="/fe/javascript/function_cache.html" class="sidebar-link">面试官：Javascript中如何实现函数缓存？函数缓存有哪些应用场景？</a></li><li><a href="/fe/javascript/loss_accuracy.html" class="sidebar-link">面试官：说说 Javascript 数字精度丢失的问题，如何解决？</a></li><li><a href="/fe/javascript/debounce_throttle.html" class="sidebar-link">防抖和节流</a></li><li><a href="/fe/javascript/visible.html" class="sidebar-link">面试官：如何判断一个元素是否在可视区域中？</a></li><li><a href="/fe/javascript/continue_to_upload.html" class="sidebar-link">面试官：大文件上传如何做断点续传？</a></li><li><a href="/fe/javascript/pull_up_loading_pull_down_refresh.html" class="sidebar-link">面试官：如何实现上拉加载，下拉刷新？</a></li><li><a href="/fe/javascript/single_sign.html" class="sidebar-link">面试官：什么是单点登录？如何实现？</a></li><li><a href="/fe/javascript/var_let_const.html" class="sidebar-link">var 、let 和 const 区别？实现原理是什么？</a></li><li><a href="/fe/javascript/null_undefined.html" class="sidebar-link">undefined与null的区别</a></li><li><a href="/fe/javascript/data_type.html" class="sidebar-link">数据类型</a></li><li><a href="/fe/javascript/js.html" class="sidebar-link">JavaScript</a></li></ul></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>TypeScript</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>ES6</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>Vue</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>Vue3</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>React</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>Webpack</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>Node.js</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>性能优化</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>手写代码</span> <span class="arrow right"></span></p> <!----></section></li></ul> </aside> <main class="page"> <div class="theme-default-content content__default"><h1 id="面试官-说说你对正则表达式的理解-应用场景"><a href="#面试官-说说你对正则表达式的理解-应用场景" class="header-anchor">#</a> 面试官：说说你对正则表达式的理解？应用场景？</h1> <p><img src="https://static.vue-js.com/55388a40-7f1d-11eb-ab90-d9ae814b240d.png" alt=""></p> <h2 id="一、是什么"><a href="#一、是什么" class="header-anchor">#</a> 一、是什么</h2> <p>正则表达式是一种用来匹配字符串的强有力的武器</p> <p>它的设计思想是用一种描述性的语言定义一个规则，凡是符合规则的字符串，我们就认为它“匹配”了，否则，该字符串就是不合法的</p> <p>在 <code>JavaScript</code>中，正则表达式也是对象，构建正则表达式有两种方式：</p> <ol><li>字面量创建，其由包含在斜杠之间的模式组成</li></ol> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">const</span> re <span class="token operator">=</span> <span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">\d+</span><span class="token regex-delimiter">/</span><span class="token regex-flags">g</span></span><span class="token punctuation">;</span>
</code></pre></div><ol start="2"><li>调用<code>RegExp</code>对象的构造函数</li></ol> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">const</span> re <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">RegExp</span><span class="token punctuation">(</span><span class="token string">&quot;\\d+&quot;</span><span class="token punctuation">,</span><span class="token string">&quot;g&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>

<span class="token keyword">const</span> rul <span class="token operator">=</span> <span class="token string">&quot;\\d+&quot;</span>
<span class="token keyword">const</span> re1 <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">RegExp</span><span class="token punctuation">(</span>rul<span class="token punctuation">,</span><span class="token string">&quot;g&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre></div><p>使用构建函数创建，第一个参数可以是一个变量，遇到特殊字符<code>\</code>需要使用<code>\\</code>进行转义</p> <h2 id="二、匹配规则"><a href="#二、匹配规则" class="header-anchor">#</a> 二、匹配规则</h2> <p>常见的校验规则如下：</p> <table><thead><tr><th>规则</th> <th>描述</th></tr></thead> <tbody><tr><td>\</td> <td>转义</td></tr> <tr><td>^</td> <td>匹配输入的开始</td></tr> <tr><td>$</td> <td>匹配输入的结束</td></tr> <tr><td>*</td> <td>匹配前一个表达式 0 次或多次</td></tr> <tr><td>+</td> <td>匹配前面一个表达式 1 次或者多次。等价于 <code>{1,}</code></td></tr> <tr><td>?</td> <td>匹配前面一个表达式 0 次或者 1 次。等价于<code>{0,1}</code></td></tr> <tr><td>.</td> <td>默认匹配除换行符之外的任何单个字符</td></tr> <tr><td>x(?=y)</td> <td>匹配'x'仅仅当'x'后面跟着'y'。这种叫做先行断言</td></tr> <tr><td>(?&lt;=y)x</td> <td>匹配'x'仅当'x'前面是'y'.这种叫做后行断言</td></tr> <tr><td>x(?!y)</td> <td>仅仅当'x'后面不跟着'y'时匹配'x'，这被称为正向否定查找</td></tr> <tr><td>(?&lt;!<em>y</em>)<em>x</em></td> <td>仅仅当'x'前面不是'y'时匹配'x'，这被称为反向否定查找</td></tr> <tr><td>x|y</td> <td>匹配‘x’或者‘y’</td></tr> <tr><td>{n}</td> <td>n 是一个正整数，匹配了前面一个字符刚好出现了 n 次</td></tr> <tr><td>{n,}</td> <td>n是一个正整数，匹配前一个字符至少出现了n次</td></tr> <tr><td>{n,m}</td> <td>n 和 m 都是整数。匹配前面的字符至少n次，最多m次</td></tr> <tr><td>[xyz]</td> <td>一个字符集合。匹配方括号中的任意字符</td></tr> <tr><td>[^xyz]</td> <td>匹配任何没有包含在方括号中的字符</td></tr> <tr><td>\b</td> <td>匹配一个词的边界，例如在字母和空格之间</td></tr> <tr><td>\B</td> <td>匹配一个非单词边界</td></tr> <tr><td>\d</td> <td>匹配一个数字</td></tr> <tr><td>\D</td> <td>匹配一个非数字字符</td></tr> <tr><td>\f</td> <td>匹配一个换页符</td></tr> <tr><td>\n</td> <td>匹配一个换行符</td></tr> <tr><td>\r</td> <td>匹配一个回车符</td></tr> <tr><td>\s</td> <td>匹配一个空白字符，包括空格、制表符、换页符和换行符</td></tr> <tr><td>\S</td> <td>匹配一个非空白字符</td></tr> <tr><td>\w</td> <td>匹配一个单字字符（字母、数字或者下划线）</td></tr> <tr><td>\W</td> <td>匹配一个非单字字符</td></tr></tbody></table> <h3 id="正则表达式标记"><a href="#正则表达式标记" class="header-anchor">#</a> 正则表达式标记</h3> <table><thead><tr><th style="text-align:left;">标志</th> <th style="text-align:left;">描述</th></tr></thead> <tbody><tr><td style="text-align:left;"><code>g</code></td> <td style="text-align:left;">全局搜索。</td></tr> <tr><td style="text-align:left;"><code>i</code></td> <td style="text-align:left;">不区分大小写搜索。</td></tr> <tr><td style="text-align:left;"><code>m</code></td> <td style="text-align:left;">多行搜索。</td></tr> <tr><td style="text-align:left;"><code>s</code></td> <td style="text-align:left;">允许 <code>.</code> 匹配换行符。</td></tr> <tr><td style="text-align:left;"><code>u</code></td> <td style="text-align:left;">使用<code>unicode</code>码的模式进行匹配。</td></tr> <tr><td style="text-align:left;"><code>y</code></td> <td style="text-align:left;">执行“粘性(<code>sticky</code>)”搜索,匹配从目标字符串的当前位置开始。</td></tr></tbody></table> <p>使用方法如下：</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">var</span> re <span class="token operator">=</span> <span class="token operator">/</span>pattern<span class="token operator">/</span>flags<span class="token punctuation">;</span>
<span class="token keyword">var</span> re <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">RegExp</span><span class="token punctuation">(</span><span class="token string">&quot;pattern&quot;</span><span class="token punctuation">,</span> <span class="token string">&quot;flags&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre></div><p>在了解下正则表达式基本的之外，还可以掌握几个正则表达式的特性：</p> <h3 id="贪婪模式"><a href="#贪婪模式" class="header-anchor">#</a> 贪婪模式</h3> <p>在了解贪婪模式前，首先举个例子：</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">const</span> reg <span class="token operator">=</span> <span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">ab{1,3}c</span><span class="token regex-delimiter">/</span></span>
</code></pre></div><p>在匹配过程中，尝试可能的顺序是从多往少的方向去尝试。首先会尝试<code>bbb</code>，然后再看整个正则是否能匹配。不能匹配时，吐出一个<code>b</code>，即在<code>bb</code>的基础上，再继续尝试，以此重复</p> <p>如果多个贪婪量词挨着，则深度优先搜索</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">const</span> string <span class="token operator">=</span> <span class="token string">&quot;12345&quot;</span><span class="token punctuation">;</span>
<span class="token keyword">const</span> regx <span class="token operator">=</span> <span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">(\d{1,3})(\d{1,3})</span><span class="token regex-delimiter">/</span></span><span class="token punctuation">;</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span> string<span class="token punctuation">.</span><span class="token function">match</span><span class="token punctuation">(</span>reg<span class="token punctuation">)</span> <span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// =&gt; [&quot;12345&quot;, &quot;123&quot;, &quot;45&quot;, index: 0, input: &quot;12345&quot;]</span>
</code></pre></div><p>其中，前面的<code>\d{1,3}</code>匹配的是&quot;123&quot;，后面的<code>\d{1,3}</code>匹配的是&quot;45&quot;</p> <h3 id="懒惰模式"><a href="#懒惰模式" class="header-anchor">#</a> 懒惰模式</h3> <p>惰性量词就是在贪婪量词后面加个问号。表示尽可能少的匹配</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">var</span> string <span class="token operator">=</span> <span class="token string">&quot;12345&quot;</span><span class="token punctuation">;</span>
<span class="token keyword">var</span> regex <span class="token operator">=</span> <span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">(\d{1,3}?)(\d{1,3})</span><span class="token regex-delimiter">/</span></span><span class="token punctuation">;</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span> string<span class="token punctuation">.</span><span class="token function">match</span><span class="token punctuation">(</span>regex<span class="token punctuation">)</span> <span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// =&gt; [&quot;1234&quot;, &quot;1&quot;, &quot;234&quot;, index: 0, input: &quot;12345&quot;]</span>
</code></pre></div><p>其中<code>\d{1,3}?</code>只匹配到一个字符&quot;1&quot;，而后面的<code>\d{1,3}</code>匹配了&quot;234&quot;</p> <h3 id="分组"><a href="#分组" class="header-anchor">#</a> 分组</h3> <p>分组主要是用过<code>()</code>进行实现，比如<code>beyond{3}</code>，是匹配<code>d</code>字母3次。而<code>(beyond){3}</code>是匹配<code>beyond</code>三次</p> <p>在<code>()</code>内使用<code>|</code>达到或的效果，如<code>(abc | xxx)</code>可以匹配<code>abc</code>或者<code>xxx</code></p> <p>反向引用，巧用<code>$</code>分组捕获</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> str <span class="token operator">=</span> <span class="token string">&quot;John Smith&quot;</span><span class="token punctuation">;</span>

<span class="token comment">// 交换名字和姓氏</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>str<span class="token punctuation">.</span><span class="token function">replace</span><span class="token punctuation">(</span><span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">(john) (smith)</span><span class="token regex-delimiter">/</span><span class="token regex-flags">i</span></span><span class="token punctuation">,</span> <span class="token string">'$2, $1'</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token comment">// Smith, John</span>
</code></pre></div><h2 id="三、匹配方法"><a href="#三、匹配方法" class="header-anchor">#</a> 三、匹配方法</h2> <p>正则表达式常被用于某些方法，我们可以分成两类：</p> <ul><li>字符串（str）方法：<code>match</code>、<code>matchAll</code>、<code>search</code>、<code>replace</code>、<code>split</code></li> <li>正则对象下（regexp）的方法：<code>test</code>、<code>exec</code></li></ul> <table><thead><tr><th style="text-align:left;">方法</th> <th style="text-align:left;">描述</th></tr></thead> <tbody><tr><td style="text-align:left;">exec</td> <td style="text-align:left;">一个在字符串中执行查找匹配的RegExp方法，它返回一个数组（未匹配到则返回 null）。</td></tr> <tr><td style="text-align:left;">test</td> <td style="text-align:left;">一个在字符串中测试是否匹配的RegExp方法，它返回 true 或 false。</td></tr> <tr><td style="text-align:left;">match</td> <td style="text-align:left;">一个在字符串中执行查找匹配的String方法，它返回一个数组，在未匹配到时会返回 null。</td></tr> <tr><td style="text-align:left;">matchAll</td> <td style="text-align:left;">一个在字符串中执行查找所有匹配的String方法，它返回一个迭代器（iterator）。</td></tr> <tr><td style="text-align:left;">search</td> <td style="text-align:left;">一个在字符串中测试匹配的String方法，它返回匹配到的位置索引，或者在失败时返回-1。</td></tr> <tr><td style="text-align:left;">replace</td> <td style="text-align:left;">一个在字符串中执行查找匹配的String方法，并且使用替换字符串替换掉匹配到的子字符串。</td></tr> <tr><td style="text-align:left;">split</td> <td style="text-align:left;">一个使用正则表达式或者一个固定字符串分隔一个字符串，并将分隔后的子字符串存储到数组中的 <code>String</code> 方法。</td></tr></tbody></table> <h3 id="str-match-regexp"><a href="#str-match-regexp" class="header-anchor">#</a> str.match(regexp)</h3> <p><code>str.match(regexp)</code> 方法在字符串 <code>str</code> 中找到匹配 <code>regexp</code> 的字符</p> <p>如果 <code>regexp</code> 不带有 <code>g</code> 标记，则它以数组的形式返回第一个匹配项，其中包含分组和属性 <code>index</code>（匹配项的位置）、<code>input</code>（输入字符串，等于 <code>str</code>）</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> str <span class="token operator">=</span> <span class="token string">&quot;I love JavaScript&quot;</span><span class="token punctuation">;</span>

<span class="token keyword">let</span> result <span class="token operator">=</span> str<span class="token punctuation">.</span><span class="token function">match</span><span class="token punctuation">(</span><span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">Java(Script)</span><span class="token regex-delimiter">/</span></span><span class="token punctuation">)</span><span class="token punctuation">;</span>

console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span> result<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span> <span class="token punctuation">)</span><span class="token punctuation">;</span>     <span class="token comment">// JavaScript（完全匹配）</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span> result<span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">]</span> <span class="token punctuation">)</span><span class="token punctuation">;</span>     <span class="token comment">// Script（第一个分组）</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span> result<span class="token punctuation">.</span>length <span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 2</span>

<span class="token comment">// 其他信息：</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span> result<span class="token punctuation">.</span>index <span class="token punctuation">)</span><span class="token punctuation">;</span>  <span class="token comment">// 7（匹配位置）</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span> result<span class="token punctuation">.</span>input <span class="token punctuation">)</span><span class="token punctuation">;</span>  <span class="token comment">// I love JavaScript（源字符串）</span>
</code></pre></div><p>如果 <code>regexp</code> 带有 <code>g</code> 标记，则它将所有匹配项的数组作为字符串返回，而不包含分组和其他详细信息</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> str <span class="token operator">=</span> <span class="token string">&quot;I love JavaScript&quot;</span><span class="token punctuation">;</span>

<span class="token keyword">let</span> result <span class="token operator">=</span> str<span class="token punctuation">.</span><span class="token function">match</span><span class="token punctuation">(</span><span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">Java(Script)</span><span class="token regex-delimiter">/</span><span class="token regex-flags">g</span></span><span class="token punctuation">)</span><span class="token punctuation">;</span>

console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span> result<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span> <span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// JavaScript</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span> result<span class="token punctuation">.</span>length <span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 1</span>
</code></pre></div><p>如果没有匹配项，则无论是否带有标记 <code>g</code> ，都将返回 <code>null</code></p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> str <span class="token operator">=</span> <span class="token string">&quot;I love JavaScript&quot;</span><span class="token punctuation">;</span>

<span class="token keyword">let</span> result <span class="token operator">=</span> str<span class="token punctuation">.</span><span class="token function">match</span><span class="token punctuation">(</span><span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">HTML</span><span class="token regex-delimiter">/</span></span><span class="token punctuation">)</span><span class="token punctuation">;</span>

console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>result<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// null</span>
</code></pre></div><h3 id="str-matchall-regexp"><a href="#str-matchall-regexp" class="header-anchor">#</a> str.matchAll(regexp)</h3> <p>返回一个包含所有匹配正则表达式的结果及分组捕获组的迭代器</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">const</span> regexp <span class="token operator">=</span> <span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">t(e)(st(\d?))</span><span class="token regex-delimiter">/</span><span class="token regex-flags">g</span></span><span class="token punctuation">;</span>
<span class="token keyword">const</span> str <span class="token operator">=</span> <span class="token string">'test1test2'</span><span class="token punctuation">;</span>

<span class="token keyword">const</span> array <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token operator">...</span>str<span class="token punctuation">.</span><span class="token function">matchAll</span><span class="token punctuation">(</span>regexp<span class="token punctuation">)</span><span class="token punctuation">]</span><span class="token punctuation">;</span>

console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>array<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// expected output: Array [&quot;test1&quot;, &quot;e&quot;, &quot;st1&quot;, &quot;1&quot;]</span>

console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>array<span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// expected output: Array [&quot;test2&quot;, &quot;e&quot;, &quot;st2&quot;, &quot;2&quot;]</span>
</code></pre></div><h3 id="str-search-regexp"><a href="#str-search-regexp" class="header-anchor">#</a> str.search(regexp)</h3> <p>返回第一个匹配项的位置，如果未找到，则返回 <code>-1</code></p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> str <span class="token operator">=</span> <span class="token string">&quot;A drop of ink may make a million think&quot;</span><span class="token punctuation">;</span>

console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span> str<span class="token punctuation">.</span><span class="token function">search</span><span class="token punctuation">(</span> <span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">ink</span><span class="token regex-delimiter">/</span><span class="token regex-flags">i</span></span> <span class="token punctuation">)</span> <span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 10（第一个匹配位置）</span>
</code></pre></div><p>这里需要注意的是，<code>search</code> 仅查找第一个匹配项</p> <h2 id="str-replace-regexp"><a href="#str-replace-regexp" class="header-anchor">#</a> str.replace(regexp)</h2> <p>替换与正则表达式匹配的子串，并返回替换后的字符串。在不设置全局匹配<code>g</code>的时候，只替换第一个匹配成功的字符串片段</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">const</span> reg1<span class="token operator">=</span><span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">javascript</span><span class="token regex-delimiter">/</span><span class="token regex-flags">i</span></span><span class="token punctuation">;</span>
<span class="token keyword">const</span> reg2<span class="token operator">=</span><span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">javascript</span><span class="token regex-delimiter">/</span><span class="token regex-flags">ig</span></span><span class="token punctuation">;</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'hello Javascript Javascript Javascript'</span><span class="token punctuation">.</span><span class="token function">replace</span><span class="token punctuation">(</span>reg1<span class="token punctuation">,</span><span class="token string">'js'</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">//hello js Javascript Javascript</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'hello Javascript Javascript Javascript'</span><span class="token punctuation">.</span><span class="token function">replace</span><span class="token punctuation">(</span>reg2<span class="token punctuation">,</span><span class="token string">'js'</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">//hello js js js</span>
</code></pre></div><h3 id="str-split-regexp"><a href="#str-split-regexp" class="header-anchor">#</a> str.split(regexp)</h3> <p>使用正则表达式（或子字符串）作为分隔符来分割字符串</p> <div class="language-js extra-class"><pre class="language-js"><code>console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'12, 34, 56'</span><span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">,\s*</span><span class="token regex-delimiter">/</span></span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token comment">// 数组 ['12', '34', '56']</span>
</code></pre></div><h3 id="regexp-exec-str"><a href="#regexp-exec-str" class="header-anchor">#</a> regexp.exec(str)</h3> <p><code>regexp.exec(str)</code> 方法返回字符串 <code>str</code> 中的 <code>regexp</code> 匹配项，与以前的方法不同，它是在正则表达式而不是字符串上调用的</p> <p>根据正则表达式是否带有标志 <code>g</code>，它的行为有所不同</p> <p>如果没有 <code>g</code>，那么 <code>regexp.exec(str)</code> 返回的第一个匹配与 <code>str.match(regexp)</code> 完全相同</p> <p>如果有标记 <code>g</code>，调用 <code>regexp.exec(str)</code> 会返回第一个匹配项，并将紧随其后的位置保存在属性<code>regexp.lastIndex</code> 中。 下一次同样的调用会从位置 <code>regexp.lastIndex</code> 开始搜索，返回下一个匹配项，并将其后的位置保存在 <code>regexp.lastIndex</code> 中</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> str <span class="token operator">=</span> <span class="token string">'More about JavaScript at https://javascript.info'</span><span class="token punctuation">;</span>
<span class="token keyword">let</span> regexp <span class="token operator">=</span> <span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">javascript</span><span class="token regex-delimiter">/</span><span class="token regex-flags">ig</span></span><span class="token punctuation">;</span>

<span class="token keyword">let</span> result<span class="token punctuation">;</span>

<span class="token keyword">while</span> <span class="token punctuation">(</span>result <span class="token operator">=</span> regexp<span class="token punctuation">.</span><span class="token function">exec</span><span class="token punctuation">(</span>str<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
  console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span> <span class="token template-string"><span class="token template-punctuation string">`</span><span class="token string">Found </span><span class="token interpolation"><span class="token interpolation-punctuation punctuation">${</span>result<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span><span class="token interpolation-punctuation punctuation">}</span></span><span class="token string"> at position </span><span class="token interpolation"><span class="token interpolation-punctuation punctuation">${</span>result<span class="token punctuation">.</span>index<span class="token interpolation-punctuation punctuation">}</span></span><span class="token template-punctuation string">`</span></span> <span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token comment">// Found JavaScript at position 11</span>
  <span class="token comment">// Found javascript at position 33</span>
<span class="token punctuation">}</span>
</code></pre></div><h3 id="regexp-test-str"><a href="#regexp-test-str" class="header-anchor">#</a> regexp.test(str)</h3> <p>查找匹配项，然后返回 <code>true/false</code> 表示是否存在</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> str <span class="token operator">=</span> <span class="token string">&quot;I love JavaScript&quot;</span><span class="token punctuation">;</span>

<span class="token comment">// 这两个测试相同</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span> <span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">love</span><span class="token regex-delimiter">/</span><span class="token regex-flags">i</span></span><span class="token punctuation">.</span><span class="token function">test</span><span class="token punctuation">(</span>str<span class="token punctuation">)</span> <span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// true</span>
</code></pre></div><h2 id="四、应用场景"><a href="#四、应用场景" class="header-anchor">#</a> 四、应用场景</h2> <p>通过上面的学习，我们对正则表达式有了一定的了解</p> <p>下面再来看看正则表达式一些案例场景：</p> <p>验证QQ合法性（5~15位、全是数字、不以0开头）：</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">const</span> reg <span class="token operator">=</span> <span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">^[1-9][0-9]{4,14}$</span><span class="token regex-delimiter">/</span></span>
<span class="token keyword">const</span> isvalid <span class="token operator">=</span> patrn<span class="token punctuation">.</span><span class="token function">exec</span><span class="token punctuation">(</span>s<span class="token punctuation">)</span>
</code></pre></div><p>校验用户账号合法性（只能输入5-20个以字母开头、可带数字、“_”、“.”的字串）：</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">var</span> patrn<span class="token operator">=</span><span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">^[a-zA-Z]{1}([a-zA-Z0-9]|[._]){4,19}$</span><span class="token regex-delimiter">/</span></span><span class="token punctuation">;</span>
<span class="token keyword">const</span> isvalid <span class="token operator">=</span> patrn<span class="token punctuation">.</span><span class="token function">exec</span><span class="token punctuation">(</span>s<span class="token punctuation">)</span>
</code></pre></div><p>将<code>url</code>参数解析为对象</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">const</span> protocol <span class="token operator">=</span> <span class="token string">'(?&lt;protocol&gt;https?:)'</span><span class="token punctuation">;</span>
<span class="token keyword">const</span> host <span class="token operator">=</span> <span class="token string">'(?&lt;host&gt;(?&lt;hostname&gt;[^/#?:]+)(?::(?&lt;port&gt;\\d+))?)'</span><span class="token punctuation">;</span>
<span class="token keyword">const</span> path <span class="token operator">=</span> <span class="token string">'(?&lt;pathname&gt;(?:\\/[^/#?]+)*\\/?)'</span><span class="token punctuation">;</span>
<span class="token keyword">const</span> search <span class="token operator">=</span> <span class="token string">'(?&lt;search&gt;(?:\\?[^#]*)?)'</span><span class="token punctuation">;</span>
<span class="token keyword">const</span> hash <span class="token operator">=</span> <span class="token string">'(?&lt;hash&gt;(?:#.*)?)'</span><span class="token punctuation">;</span>
<span class="token keyword">const</span> reg <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">RegExp</span><span class="token punctuation">(</span><span class="token template-string"><span class="token template-punctuation string">`</span><span class="token string">^</span><span class="token interpolation"><span class="token interpolation-punctuation punctuation">${</span>protocol<span class="token interpolation-punctuation punctuation">}</span></span><span class="token string">\/\/</span><span class="token interpolation"><span class="token interpolation-punctuation punctuation">${</span>host<span class="token interpolation-punctuation punctuation">}</span></span><span class="token interpolation"><span class="token interpolation-punctuation punctuation">${</span>path<span class="token interpolation-punctuation punctuation">}</span></span><span class="token interpolation"><span class="token interpolation-punctuation punctuation">${</span>search<span class="token interpolation-punctuation punctuation">}</span></span><span class="token interpolation"><span class="token interpolation-punctuation punctuation">${</span>hash<span class="token interpolation-punctuation punctuation">}</span></span><span class="token string">$</span><span class="token template-punctuation string">`</span></span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">function</span> <span class="token function">execURL</span><span class="token punctuation">(</span><span class="token parameter">url</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token keyword">const</span> result <span class="token operator">=</span> reg<span class="token punctuation">.</span><span class="token function">exec</span><span class="token punctuation">(</span>url<span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token keyword">if</span><span class="token punctuation">(</span>result<span class="token punctuation">)</span><span class="token punctuation">{</span>
        result<span class="token punctuation">.</span>groups<span class="token punctuation">.</span>port <span class="token operator">=</span> result<span class="token punctuation">.</span>groups<span class="token punctuation">.</span>port <span class="token operator">||</span> <span class="token string">''</span><span class="token punctuation">;</span>
        <span class="token keyword">return</span> result<span class="token punctuation">.</span>groups<span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
    <span class="token keyword">return</span> <span class="token punctuation">{</span>
        protocol<span class="token operator">:</span><span class="token string">''</span><span class="token punctuation">,</span>host<span class="token operator">:</span><span class="token string">''</span><span class="token punctuation">,</span>hostname<span class="token operator">:</span><span class="token string">''</span><span class="token punctuation">,</span>port<span class="token operator">:</span><span class="token string">''</span><span class="token punctuation">,</span>
        pathname<span class="token operator">:</span><span class="token string">''</span><span class="token punctuation">,</span>search<span class="token operator">:</span><span class="token string">''</span><span class="token punctuation">,</span>hash<span class="token operator">:</span><span class="token string">''</span><span class="token punctuation">,</span>
    <span class="token punctuation">}</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>

console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token function">execURL</span><span class="token punctuation">(</span><span class="token string">'https://localhost:8080/?a=b#xxxx'</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
protocol<span class="token operator">:</span> <span class="token string">&quot;https:&quot;</span>
host<span class="token operator">:</span> <span class="token string">&quot;localhost:8080&quot;</span>
hostname<span class="token operator">:</span> <span class="token string">&quot;localhost&quot;</span>
port<span class="token operator">:</span> <span class="token string">&quot;8080&quot;</span>
pathname<span class="token operator">:</span> <span class="token string">&quot;/&quot;</span>
search<span class="token operator">:</span> <span class="token string">&quot;?a=b&quot;</span>
hash<span class="token operator">:</span> <span class="token string">&quot;#xxxx&quot;</span>
</code></pre></div><p>再将上面的<code>search</code>和<code>hash</code>进行解析</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">function</span> <span class="token function">execUrlParams</span><span class="token punctuation">(</span><span class="token parameter">str</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    str <span class="token operator">=</span> str<span class="token punctuation">.</span><span class="token function">replace</span><span class="token punctuation">(</span><span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">^[#?&amp;]</span><span class="token regex-delimiter">/</span></span><span class="token punctuation">,</span><span class="token string">''</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token keyword">const</span> result <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token punctuation">}</span><span class="token punctuation">;</span>
    <span class="token keyword">if</span><span class="token punctuation">(</span><span class="token operator">!</span>str<span class="token punctuation">)</span><span class="token punctuation">{</span> <span class="token comment">//如果正则可能配到空字符串，极有可能造成死循环，判断很重要</span>
        <span class="token keyword">return</span> result<span class="token punctuation">;</span> 
    <span class="token punctuation">}</span>
    <span class="token keyword">const</span> reg <span class="token operator">=</span> <span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">(?:^|&amp;)([^&amp;=]*)=?([^&amp;]*?)(?=&amp;|$)</span><span class="token regex-delimiter">/</span><span class="token regex-flags">y</span></span>
    <span class="token keyword">let</span> exec <span class="token operator">=</span> reg<span class="token punctuation">.</span><span class="token function">exec</span><span class="token punctuation">(</span>str<span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token keyword">while</span><span class="token punctuation">(</span>exec<span class="token punctuation">)</span><span class="token punctuation">{</span>
        result<span class="token punctuation">[</span>exec<span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">]</span> <span class="token operator">=</span> exec<span class="token punctuation">[</span><span class="token number">2</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
        exec <span class="token operator">=</span> reg<span class="token punctuation">.</span><span class="token function">exec</span><span class="token punctuation">(</span>str<span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
    <span class="token keyword">return</span> result<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token function">execUrlParams</span><span class="token punctuation">(</span><span class="token string">'#'</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">// {}</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token function">execUrlParams</span><span class="token punctuation">(</span><span class="token string">'##'</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//{'#':''}</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token function">execUrlParams</span><span class="token punctuation">(</span><span class="token string">'?q=3606&amp;src=srp'</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//{q: &quot;3606&quot;, src: &quot;srp&quot;}</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token function">execUrlParams</span><span class="token punctuation">(</span><span class="token string">'test=a=b=c&amp;&amp;==&amp;a='</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//{test: &quot;a=b=c&quot;, &quot;&quot;: &quot;=&quot;, a: &quot;&quot;}</span>
</code></pre></div><h2 id="参考文献"><a href="#参考文献" class="header-anchor">#</a> 参考文献</h2> <ul><li>https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Guide/Regular_Expressions</li></ul></div> <footer class="page-edit"><!----> <div class="last-updated"><span class="prefix">更新时间:</span> <span class="time">12/14/2021, 10:12:35 AM</span></div></footer> <div class="page-nav"><p class="inner"><span class="prev">
      ←
      <a href="/fe/javascript/bind_call_apply.html" class="prev">
        面试官：bind、call、apply 区别？如何实现一个bind?
      </a></span> <span class="next"><a href="/fe/javascript/event_loop.html">
        事件循环机制
      </a>
      →
    </span></p></div> </main></div><div class="global-ui"><!----></div></div>
    <script src="/assets/js/app.bf44e39b.js" defer></script><script src="/assets/js/2.db7a59af.js" defer></script><script src="/assets/js/140.22839840.js" defer></script>
  </body>
</html>
